Sydney rail link on time, on budget: govt

SYDNEY'S North West Rail Link is on time and on budget says NSW Transport Minister Gladys Berejiklian.

The NSW opposition has accused the government of mishandling the project, claiming it's overspent by $35 million before construction even starts.

Cost blow-outs include $31 million to be spent on engineering instead of the expected $19.7 million and $8.8 million to be spent on legal services though the tender was for $735,000, said Labor's transport spokeswoman Penny Sharpe.

But Ms Berejiklian denied the allegations during question time.

"I am pleased to say the North West Rail Link is on time and on budget," she said on Wednesday.

"The government has always said the project will cost between $7.5 and $8.5 billion and that remains the case...

"I want to stress that every single dollar spent on the project to date has been completely within the allocated budget."

After accusing the Labor government of achieving nothing in 16 years of government, the minister fired back: "Stop wasting my time, you should be embarrassed".

"They can point their finger at one project they did, which was the Chatswood to Epping rail line, that was half the line at double the cost. That is their record."

The 23-kilometre North West Rail Link will connect Chatswood, on Sydney's north shore, with the Hills district in the city's northwest and will include eight new train stations.

It's expected to support more than 16,200 jobs during construction and inject about $25 billion into the state's economy.